Antistatic synthetic resin plates capable of discharging static electricity and thereby preventing adhesion of dust are used in applications which must avoid dust, such as partitions of a clean room. In addition, as certain semiconductor production apparatus such as a washing vessel and an etching vessel and auxiliary materials for use in their production, such as angles and channels, those which have antistatic property are employed.
Among them, the antistatic synthetic resin plates are produced by laminating a conductive material-containing antistatic layer on the surface of a synthetic resin plate, and various types of thermoplastic resin plates are used as the synthetic resin plates. Particularly, an antistatic vinyl chloride resin plate produced by laminating an antistatic layer on the surface of a vinyl chloride resin plate is frequently used, because the vinyl chloride resin has good moldability and is inexpensive and excellent in terms of mechanical strength and chemical resistance.
However, though these antistatic vinyl chloride resin plates and auxiliary materials made of vinyl chloride resin have fire-retardant property in some degree because of chlorine contained in the vinyl chloride resin itself, they generate smoke and corrosive gases in large amounts due to thermal decomposition of the resin when it causes a fire, so that when these materials such as antistatic vinyl chloride resin plates are used in, e.g., a clean room of semiconductor production factories, air in the factories is polluted with smoke and corrosive gasses generated at the time of a fire, thus causing a danger of polluting and corroding related assets such as production devices, equipment and semiconductor parts.
Because of such circumstances, more higher fire-retardant property is in great demand, and studies are carried out on an antistatic vinyl chloride resin plate which can satisfy this requirement. In order to increase fire-retardant property of the vinyl chloride resin plate, certain means such as inclusion of an inorganic filler in a large amount of approximately from 1.5 to 3 times of the resin content and inclusion of a halogen based fire-retarding agent have mainly been employed, but application of such means has the following problems.
That is, when an inorganic filler is contained in a large amount, not only an antistatic vinyl chloride resin plate having practical strength is difficult to obtain due to brittleness but also a transparent antistatic vinyl chloride resin plate cannot be obtained, and it also causes another problem of reducing chemical resistance of the resin plate.
On the other hand, when a halogen based fire-retarding agent is contained, fire-retardant property of the antistatic vinyl chloride resin plate can be improved but it causes a problem of generating a halogen-containing gas at the time of a fire, and inclusion of a halogen based fire-retarding agent in the transparent resin plate causes a problem of reducing the transparency.
The object of the invention is to provide a plate-shaped or other shape of an antistatic vinyl chloride resin molding having excellent fire-retardant property which can solve these problems.